1. Field of the invention
This invention relates to a key-operated touch responsive sensor to be used in an electronic keyboard musical instrument and more particularly to a sensor device for deriving controlling signals in accordance with the displacement of a key depressed in an electronic musical instrument.
2. Description of the prior art
In electronic musical instruments, a technique is utilized for minutely controlling a musical sound in accordance with the movement of a key depressed, which is called "touch control" or "touch responsive control." Such touch responsive control has so far been effected by the detection of the depression speed of a key or minute displacements thereof at key-depressed positions with the use of photoelectric elements or semiconductor pressure sensitive elements, thereby controlling the tone volume or the tone color therewith. According to such conventional techniques, however, the semiconductor elements have the defect of showing large temperature dependence characteristics, while the photoelectric elements have the shortcoming of being slow in response. Thus, additional circuits are necessary for removing such drawbacks, resulting in a complicated and expensive structure. Further, there has been proposed no touch responsive control means which detects and utilizes both the depression speed of a key and the minute displacement of the key at key-depressed positions.